Tension for band mills



Dec. 29, 1925. 1,567,911.

G. E. CAMPBELL TENSION FOR BAND MILLS Filed March 51. 1922- 4-Sheat9-Sh08t 1 Dec. 29 1925.

G. E. CAMPBELL TENSION FOR BAND M ILLS Filed March 3]., 1922 4 Sheets-Sheet 2 Dec. 29, 1925- 1,567,911

. G. E. CAMPBELL" TENSION FOR mm) MILLS Filed March 51. 1922 4 Sheets-Sheet 5 Patented Dec. 29, 1925.

Gn me e EB L or xm er f a TENNESSEE, ASSIGNQB o turn WHELAND enres? o A soee mms flawswensiee 30 em? M S- A pp lication filed March 31, 1922. Serial No. 548,352.

To all 1071 9112, it may concern:

ltpwn tha'tI, GEORG E. CAMPBELL, a cit zen of the United States, residn'i'g at Chattanooga, in the county of Hamilton and State' o f Tennessee, have 'inv'entedtertain i "new and useful Improvements in Tensions for Band Mills, of which the following 'is'a specification.

his invention' relates to an improvement in tensionslfor band Three th ngs happen to a saw-mill which make a sens tive balance under the'iop wheel ne es a y: 7

First Sawdust and other obstructions niay between the 1 saw and the lower wheel', however, this stuff does not accumulate there, as a scraper is provided on all wlieels'to remoye same.

Second :A saw sometimes becomes warm 9 whileputting, Tliisieauses the saw to panel and elongate; l

' Thirdf%lvhefi the saw first enters the log it slightly stretcl1es,diie, o "the sudden'fwork applied to the saw, andfast he log passes 5 from the and won: is' finished, the saw goes back toits original length.

All fof these 'eondition's make it necessary to have a sensitive balance under the top wheel, as? an even 'tens ion'on 'theisaw fun'd'er all'cohditidnsisdesirable.

ln' consequence"'ithas long been an object with the sawmill manufacturers toobtain as sitive a balance aslpossible inder the upper wheel; and it hasthrefore been the custom heretofore, so" far as am" aware, for most manufacturers"simply'to key" on arm to the 'cfi'oss sliaft; and"'perinittliis arm to ekt en d outin a horizontal positio i'with respect the bed of ,th eniill; and "o'n the end Qthis arm it has lieeneustoinary to hang weightsi r11? order that this arm be sufficiently strong todo its work,'it has been necessarily iheavy, and the very f veiglit of tliearm itself been anobStacIe to 'k'e'eping a sensilive tension on the" saw;

With the present design, this arm extends vertically instead orhbri'zontauy, thus doing away with the weight of the armi'tself so far as it affects tlieteiis'ion ii j'on' th e saw.

A 'iio her" of "the -'1 present Ti'n'ventio rov'ei tlieold'is n ch angin saws. With the ari' angenient,"it wasnecessary' for iot' only in Fig. 4'.

to raise and lower the upper wheel, but also the tension weights as well, whereas, under the present arrangement, all of this is o viatedi In the accompanying drawings Fig. 1 is a View in side elevation; Fig. 2 is a front View, l Fig. 3 is a detail plan View; Fig. 4 is a horizontal section; Figs. 5 and 6 are details. The numerals 1 and'2'i'epresent the upper and lower wheels, and S, the band-sz'nvl Cllhe lower wheel 2 is keyed or otherwise secured to an aile at, the ends of which are supported in journals 5he-ld below the base the usual manner. The upper wheel 1 1s mounted on the axle 7, the ends of which are journaled in boxes 8, which latter are supported in tlie/upper ends'of the yokes 9. These 'yokes have depending hollow shanks "10, each of which is slidably mounted in the upper'end of a tubular sleeve 11, which latter is vertically adjustable in the tubular colun1n12,form1nga part of the main frame of the saw-mill.

lVithin the hollow shanks 10, and tubular sleeves 11, steel rods 13 are housed, the upper end of each of theseiods being rounded and supporting a yoke 9, as shown in Fig. 1, whil'ethe lower end is tapered to aknife edge'14t,and"rests in an off-center notch 15 in the upper surface of cross-shaft 3.

Knother' offf center notch 16 on the under sideof this" shaft receives knife-edge 17 formed on the upper end of the pin 18."

This' pin' 18has threads 19, and a nut 20 having threadsfit'ted thereto has a gear, 21

keyed" to it, as at 22, and is preferablysup- The lower end of the tubular'sleevc 11 is secured to the upper end of the pin 18 by a 'pinQ i, so tli'atjby'tur ning the gearor pin- :ion 21 1t turnsthe nut 20, and through it raises or lowersthescrew 18-w1th the hollow sleeve 11';

Motion is transmitted across from, one

side or thewli'eels gland 2 to the other by shaft 25 ;"as'slionfn in /Fig. 2, upon the ends of'wvhieli' are the beveb'gears 26 meshing into bevel-gears 27 on vertical shafts 28,

ear-pinions 21, so that ivl gmthe 'pin "withthe tubular sleeve '11 is raised or lowered on one side, the corresponding parts are correspondingly raised or lowered on the other side of the mill.

The shaft 25 is adapted to be turned by a hand-wheel (not shown).

Returning now to the saw tension, which besides including the parts 3, 10, 11, 13, let, 15,16,17 and 18, also includes the verticallydisposed arm 30, keyed to the cross-shaft 3, as shown in dotted lines in Figs. 1 and 4, and in full lines in Figs. 2, 3 and 5. The upper end of this arm 30 is connected by cable 31 to the quadrant 32 secured on the shaft 33, which is capable of rocking in bearings 34, as shown in Figs. 1 and 3. A tension lever 35 extends out from this shaft 33, from which are hung weights 36.

The cable is connected to the upper end of the arm 30 by a forked yoke 37, contain ing a coiled spring 38, through which is passed an eye-bolt 39, which connects di rectly to the cable 31.

It will readily be seen that the more weight placed on the end of tension-lever 35, the greater will be the tendency to lift the upper Wheel, and thereby to put strain upon the saw S, which runs around the face of the upper and lower wheel.

In changing a saw with this arrangement, the arm 30 is swung over against the stub 40, after which the wheel can be raised or lowered through the screw 18, the nut 20, and the gear-pinion 21, as hitherto explained, without any attention to the weights 36 at all.

Claims:

1. The combination with a band saw wheel, of a bearing support therefor, a column extending toward said bearing, a rock-shaft for adjustably supporting the bearing, asubstantially vertically disposed arm, secured tothe rock-shaft and extending substantially parallel to said column to a point adjacent said bearing, and means connected with the outer end of the arm for applying tension thereto to rock said arm and the rock-shaft.

2. The combination with a band saw wheel, of a movable bearing support therefor, a column extending upwardly toward said vbearing on one side of said wheel, a rook-shaft for adjustably supporting the hearing, a. substantially vertically disposed arm secured to the rock-shaft and extending upward between the column and the wheel to a point adjacent said bearing, a substantially horizontally disposed lever, and means extending laterally from the outer end of the vertically disposed arm and connected with the lever for applying tension to the arm and rock-shaft. v

3. In tensions for band saws, the combination of a movably supported band saw bearing, a rook-shaft for adjustably supporting the bearing, a substantially verti,

cally disposed arm secured on the rockshaft, a quadrant, a cable and spring forming a connection between the vertically disposed arm and the quadrant, and a substantially horizontally disposed lever normally under tension and connected with the quadrant for applying tension through the quadrant and cable to the vertically disposed arm and rock-shaft.

4. A tension for band-mills including a movable wheel support, a rod poised to sustain the weight of said support, a vertically-disposed arm for raising and lowering the rod and the support resting thereon, and tension means connected with said arm, said tension means comprising a tensionlever and a cable connecting said lever with the vertically-disposed arm, through the medium of a coil-spring and eye-bolt.

5. The combination of a band saw wheel, a support therefor, a hollow column, a tubular sleeve within the column, a rock-shaft carried by the tubular sleeve and having off-center notches, a rod resting in one of the notches and supporting the wheel support, and means for applying tension to the rock-shaft.

6. Th combination of a band saw wheel, movable yokes for supporting said wheel, hollow columns, tubular sleeves within the columns, a rock-shaft carried by the tubular sleeves and having off-center notches, rods carried within the sleeves having knife edges at th ir lower ends resting in the uppermost notches, and their upper ends extending beneath and supporting the yokes, and means for applying tension to the rock-shaft.

7 A tension for band-mills including a rock-shaft having off-center notches, a rod resting in one of the notches, a movable yoke mounted upon the rod, a band saw wheel supported on the yoke, and means for raising the rock-shaft comprising a pin having screw-threads thereon, a nut screwed onto the threads of the pin, and means for turning the nut on the pin.

8. A tension for band-mills including a rock-shaft having off-center notches, a rod resting in one of the notches, a movable yoke mounted upon the rod, a band saw wheel supported on the yoke, means for applying tension to the rock-shaft, and means for raising and lowering the rock-shaft. comprising a pin engaging one of the notches in the rock-shaft and having screw threads thereon, a nut screwed onto the threads of the pin, and gears connected with the nut for turning the same for raising or lowering the pin.

9. A tension for band mills including a rock-shaft having off-center notches, rods resting in the uppermost notches, movable yokes mounted upon the rods, a band saw wheel supported on the yokes, pins extendng' into the low n tch s Said P having screw-threaded nuts thereon, gear pinions keyed to the nuts, a cross-shaft having bevel pinions on either end, vertical shafts having bevel pinions meshing therewith, gears meshing with the gear pinions, and means for turning the cross-shaft for raising or lowering th yokes and their connected parts.

10. The combination with an upper and lower wheel, band-saws carried thereby, movable yokes in which thebearings of the upper wheel are held, hollow columns, tubular sleeves within said columns, a cross-shaft carried by and capable of being rocked in said tubular sleeves, said cross-shafthaving oil-center notches on opposite sides at each end, rods carried Within the sleeves having knife edges at their lower ends resting in the upper notches, and their upper ends extending beneath and supporting the yokes, pins having knife edges extending up from the lower ends of the hollow sleeves into the off-center notches on the lower surface of the cross-shaft, said pins having screwthreads. nuts thereon, and gear pinionskeyed to the nuts, a cross-shaft having bevel pinions on either end, and vertical shafts having bevel pinions meshing therewith, and gears meshing with the gear pinions, means for turning said shaft whereby to raise or lower the tubular sleeves with their connected parts bodily, and means for app-lying tension to the cross shaft.

11. A tension for band-mills including a rock-shaft having oil-center notches on its opposite surfaces, a pin having a knife edge which enters one of said notches, a rod having a knife edge resting in the other notch, means for raising and lowering the rock shaft and the parts eo-operating therewith, a movable yoke resting upon the upper end of said rod, a band saw wheel supported by said yoke, and a tension device including a vertically disposed arm secured to the rockshaft, a tension lever having tension means supported upon one end thereof, a coilspring and eye-bolt connected to the vertically disposed arm, and a cable extending from the coil spring and eye-bolt to the tension lever.

In testimony whereof I atfix my signature.

GEORGE E. CAMPBELL. 

